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<td> <div>Defined in header <code>&lt;time.h&gt;</code>
 </div>
</td>
<td></td>
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</tr>
<tr class="t-dcl">
<td> <div><span class="mw-geshi c source-c"><span class="kw4">char</span><span class="sy2">*</span> asctime<span class="br0">(</span> <span class="kw4">const</span> <span class="kw1">struct</span> <a href="tm.html"><span class="kw522">tm</span></a><span class="sy2">*</span> time_ptr <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td> (1) </td>
<td class="t-dcl-nopad">  </td>
</tr>
<tr class="t-dcl t-since-c11">
<td> <div><span class="mw-geshi c source-c">errno_t asctime_s<span class="br0">(</span><span class="kw4">char</span> <span class="sy2">*</span>buf, rsize_t bufsz, <span class="kw4">const</span> <span class="kw1">struct</span> <a href="tm.html"><span class="kw522">tm</span></a> <span class="sy2">*</span>time_ptr<span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td> (2) </td>
<td> <span class="t-mark-rev t-since-c11">(since C11)</span> </td>
</tr>
<tr class="t-dcl-sep">
<td></td>
<td></td>
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</tr>
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<div class="t-li1">
<span class="t-li">1)</span> Converts given calendar time <span class="t-lc"><a href="tm.html" title="c/chrono/tm">tm</a></span> to a textual representation of the following fixed 25-character form: <span class="t-c"><span class="mw-geshi c source-c">Www Mmm dd hh<span class="sy4">:</span>mm<span class="sy4">:</span>ss yyyy\n</span></span>
<ul>
<li>
<code>Www</code> - three-letter English abbreviated day of the week from <span class="t-c"><span class="mw-geshi c source-c">time_ptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_wday</span></span>, one of <code>Mon</code>, <code>Tue</code>, <code>Wed</code>, <code>Thu</code>, <code>Fri</code>, <code>Sat</code>, <code>Sun</code>.
</li>
<li>
<code>Mmm</code> - three-letter English abbreviated month name from <span class="t-c"><span class="mw-geshi c source-c">time_ptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_mon</span></span>, one of <code>Jan</code>, <code>Feb</code>, <code>Mar</code>, <code>Apr</code>, <code>May</code>, <code>Jun</code>, <code>Jul</code>, <code>Aug</code>, <code>Sep</code>, <code>Oct</code>, <code>Nov</code>, <code>Dec</code>.
</li>
<li>
<code>dd</code> - 2-digit day of the month from <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_mday</span></span> as if printed by <span class="t-lc"><a href="../io/fprintf.html" title="c/io/fprintf">sprintf</a></span> using <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span>2d</span></span>
</li>
<li>
<code>hh</code> - 2-digit hour from <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_hour</span></span> as if printed by <span class="t-lc"><a href="../io/fprintf.html" title="c/io/fprintf">sprintf</a></span> using <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span>.2d</span></span>
</li>
<li>
<code>mm</code> - 2-digit minute from <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_min</span></span> as if printed by <span class="t-lc"><a href="../io/fprintf.html" title="c/io/fprintf">sprintf</a></span> using <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span>.2d</span></span>
</li>
<li>
<code>ss</code> - 2-digit second from <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_sec</span></span> as if printed by <span class="t-lc"><a href="../io/fprintf.html" title="c/io/fprintf">sprintf</a></span> using <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span>.2d</span></span>
</li>
<li>
<code>yyyy</code> - 4-digit year from <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_year <span class="sy2">+</span> <span class="nu0">1900</span></span></span> as if printed by <span class="t-lc"><a href="../io/fprintf.html" title="c/io/fprintf">sprintf</a></span> using <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span>4d</span></span>
</li>
</ul>
</div>

<div class="t-li1">
<span class="t-li"></span> The behavior is undefined if any member of <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>time_ptr</span></span> is outside its normal range</div>
<div class="t-li1">
<span class="t-li"></span> The behavior is undefined if the calendar year indicated by <span class="t-c"><span class="mw-geshi c source-c">time_ptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_year</span></span> has more than 4 digits or is less than the year 1000.</div>
<div class="t-li1">
<span class="t-li"></span> The function does not support localization, and the newline character cannot be removed.</div>
<div class="t-li1">
<span class="t-li"></span> The function modifies static storage and is not thread-safe.</div>
<div class="t-li1">
<span class="t-li">2)</span> Same as <span class="t-v">(1)</span>, except that the message is copied into user-provided storage <code>buf</code>, which is guaranteed to be null-terminated, and the following errors are detected at runtime and call the currently installed <a href="../error/set_constraint_handler_s.html" title="c/error/set constraint handler s">constraint handler</a> function:
<dl>
<dd>
<ul>
<li> <code>buf</code> or <code>time_ptr</code> is a null pointer
</li>
<li> <code>bufsz</code> is less than 26 or greater than <span class="t-lc">RSIZE_MAX</span>
</li>
<li> not all members of <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span>time_ptr</span></span> are within their normal ranges
</li>
<li> the year indicated by <span class="t-c"><span class="mw-geshi c source-c">time_ptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_year</span></span> is less than 0 or greater than 9999
</li>
</ul>
</dd>
<dd>As all bounds-checked functions, <code>asctime_s</code> is only guaranteed to be available if <span class="t-c"><span class="mw-geshi c source-c">__STDC_LIB_EXT1__</span></span> is defined by the implementation and if the user defines <span class="t-c"><span class="mw-geshi c source-c">__STDC_WANT_LIB_EXT1__</span></span> to the integer constant <span class="t-c"><span class="mw-geshi c source-c"><span class="nu0">1</span></span></span> before including <code>time.h</code>.</dd>
</dl>
</div>

<table id="toc" class="toc"><tr><td>
<div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="asctime.html#Parameters"><span class="tocnumber">1</span> <span class="toctext">Parameters</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="asctime.html#Return_value"><span class="tocnumber">2</span> <span class="toctext">Return value</span></a></li>
<li class="toclevel-1 tocsection-3"><a href="asctime.html#Notes"><span class="tocnumber">3</span> <span class="toctext">Notes</span></a></li>
<li class="toclevel-1 tocsection-4"><a href="asctime.html#Example"><span class="tocnumber">4</span> <span class="toctext">Example</span></a></li>
<li class="toclevel-1 tocsection-5"><a href="asctime.html#References"><span class="tocnumber">5</span> <span class="toctext">References</span></a></li>
<li class="toclevel-1 tocsection-6"><a href="asctime.html#See_also"><span class="tocnumber">6</span> <span class="toctext">See also</span></a></li>
</ul>
</td></tr></table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Parameters">edit</a>]</span> <span class="mw-headline" id="Parameters">Parameters</span>
</h3>
<table class="t-par-begin">


<tr class="t-par">
<td>  time_ptr
</td>
<td> -
</td>
<td>  pointer to a <span class="t-lc"><a href="tm.html" title="c/chrono/tm">tm</a></span> object specifying the time to print
</td>
</tr>
<tr class="t-par">
<td>  buf
</td>
<td> -
</td>
<td>  pointer to a user-supplied buffer at least 26 bytes in length
</td>
</tr>
<tr class="t-par">
<td>  bufsz
</td>
<td> -
</td>
<td>  size of the user-supplied buffer
</td>
</tr>
</table>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Return value">edit</a>]</span> <span class="mw-headline" id="Return_value">Return value</span>
</h3>
<div class="t-li1">
<span class="t-li">1)</span> pointer to a static null-terminated character string holding the textual representation of date and time as described above. The string may be shared between <code>asctime</code> and <span class="t-lc"><a href="ctime.html" title="c/chrono/ctime">ctime</a></span>, and may be overwritten on each invocation of any of those functions.</div>
<div class="t-li1">
<span class="t-li">2)</span> zero on success, non-zero on failure, in which case <span class="t-c"><span class="mw-geshi c source-c">buf<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span></span></span> is set to zero (unless <code>buf</code> is a null pointer or <code>bufsz</code> is zero or greater than <span class="t-lc">RSIZE_MAX</span>).</div>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Notes">edit</a>]</span> <span class="mw-headline" id="Notes">Notes</span>
</h3>
<p>This function returns a pointer to static data and is not thread-safe. POSIX marks this function obsolete and recommends <span class="t-lc"><a href="strftime.html" title="c/chrono/strftime">strftime</a></span> instead. The C standard also recommends <span class="t-lc"><a href="strftime.html" title="c/chrono/strftime">strftime</a></span> instead of <code>asctime</code> and <code>asctime_s</code> because <code>strftime</code> is more flexible and locale-sensitive.
</p>
<p>POSIX limits undefined behaviors only to when the output string would be longer than 25 characters, when <code>timeptr-&gt;tm_wday</code> or <code>timeptr-&gt;tm_mon</code> are not within the expected ranges, or when <code>timeptr-&gt;tm_year</code> exceeds <span class="t-c"><span class="mw-geshi c source-c">INT_MAX<span class="sy2">-</span><span class="nu0">1990</span></span></span>.
</p>
<p>Some implementations handle <span class="t-c"><span class="mw-geshi c source-c">timeptr<span class="sy2">-</span><span class="sy1">&gt;</span>tm_mday<span class="sy1">==</span><span class="nu0">0</span></span></span> as meaning the last day of the preceding month.
</p>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: Example">edit</a>]</span> <span class="mw-headline" id="Example">Example</span>
</h3>
<div class="t-example">
<div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="c source-c"><pre class="de1"><span class="co2">#define __STDC_WANT_LIB_EXT1__ 1</span>
<span class="co2">#include &lt;time.h&gt;</span>
<span class="co2">#include &lt;stdio.h&gt;</span>
 
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
<span class="br0">{</span>
    <span class="kw1">struct</span> <a href="tm.html"><span class="kw522">tm</span></a> <a href="tm.html"><span class="kw522">tm</span></a> <span class="sy1">=</span> <span class="sy2">*</span><a href="localtime.html"><span class="kw519">localtime</span></a><span class="br0">(</span><span class="sy3">&amp;</span><span class="br0">(</span><a href="time_t.html"><span class="kw523">time_t</span></a><span class="br0">)</span><span class="br0">{</span><a href="time.html"><span class="kw513">time</span></a><span class="br0">(</span><a href="../types/NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span><span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
    <a href="../io/fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"%s"</span>, asctime<span class="br0">(</span><span class="sy3">&amp;</span><a href="tm.html"><span class="kw522">tm</span></a><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
 
<span class="co2">#ifdef __STDC_LIB_EXT1__</span>
    <span class="kw4">char</span> str<span class="br0">[</span><span class="nu0">26</span><span class="br0">]</span><span class="sy4">;</span>
    asctime_s<span class="br0">(</span>str, <span class="kw4">sizeof</span> str, <span class="sy3">&amp;</span><a href="tm.html"><span class="kw522">tm</span></a><span class="br0">)</span><span class="sy4">;</span>
    <a href="../io/fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"%s"</span>, str<span class="br0">)</span><span class="sy4">;</span>
<span class="co2">#endif</span>
<span class="br0">}</span></pre></div></div>
<p>Possible output:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="text source-text"><pre class="de1">Tue May 26 21:51:50 2015
Tue May 26 21:51:50 2015</pre></div></div> 
</div>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: References">edit</a>]</span> <span class="mw-headline" id="References">References</span>
</h3>
<div class="t-ref-std-11">
<ul><li> C11 standard (ISO/IEC 9899:2011): 
</li></ul>
<dl><dd>
<ul><li> 7.27.2.1 The asctime function (p: 392-393)
</li></ul>
</dd></dl>
<dl><dd>
<ul><li> K.3.8.2.1 The asctime_s function (p: 624-625)
</li></ul>
</dd></dl>
<div class="t-ref-std-c99">
<ul><li> C99 standard (ISO/IEC 9899:1999): 
</li></ul>
<dl><dd>
<ul><li> 7.23.3.1 The asctime function (p: 341-342)
</li></ul>
</dd></dl>
<div class="t-ref-std-c89">
<ul><li> C89/C90 standard (ISO/IEC 9899:1990): 
</li></ul>
<dl><dd>
<ul><li> 4.12.3.1 The asctime function 
</li></ul>
</dd></dl>
</div>
<h3>
<span class="editsection">[<a href="http%3A//en.cppreference.com/mwiki/index.php" title="Edit section: See also">edit</a>]</span> <span class="mw-headline" id="See_also">See also</span>
</h3>
<table class="t-dsc-begin">

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div">
<div><a href="ctime.html" title="c/chrono/ctime"> <span class="t-lines"><span>ctime</span><span>ctime_s</span></span></a></div>
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
</div>
</td>
<td>   converts a <code>time_t</code> object to a textual representation <br> <span class="t-mark">(function)</span> 
</td>
</tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="strftime.html" title="c/chrono/strftime"> <span class="t-lines"><span>strftime</span></span></a></div></div>
</td>
<td>   converts a <code>tm</code> object to custom textual representation <br> <span class="t-mark">(function)</span> 
</td>
</tr>

<tr class="t-dsc">
<td colspan="2"> <div class="t-dsc-see">
<span><a href="../../cpp/chrono/c/asctime.html" title="cpp/chrono/c/asctime">C++ documentation</a></span> for <span class="t-dsc-see-tt"><span>asctime</span></span>
</div>
</td>
</tr>

</table>
</div>
</div>

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